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handle exceptional flow correctly in collapse_vars (#2574)

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fixes #2571
This commit is contained in:
Alex Lam S.L
2017-12-11 00:16:02 +08:00
committed by GitHub
parent 2441827408
commit 0e16d92786
2 changed files with 203 additions and 32 deletions
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151
lib/compress.js
View File

@@ -868,6 +868,21 @@ merge(Compressor.prototype, {
var stat_index = statements.length;
var scanner = new TreeTransformer(function(node, descend) {
if (abort) return node;
// Scan case expressions first in a switch statement
if (node instanceof AST_Switch) {
node.expression = node.expression.transform(scanner);
for (var i = 0, len = node.body.length; !abort && i < len; i++) {
var branch = node.body[i];
if (branch instanceof AST_Case)
branch.expression = branch.expression.transform(scanner);
}
for (i = 0; !abort && i < len; i++) {
var branch = node.body[i];
for (var j = 0, len2 = branch.body.length; j < len2; j++)
branch.body[j] = branch.body[j].transform(scanner);
}
return node;
}
// Skip nodes before `candidate` as quickly as possible
if (!hit) {
if (node === candidate) {
@@ -944,17 +959,17 @@ merge(Compressor.prototype, {
|| side_effects && !references_in_scope(node.definition()))
|| (sym = lhs_or_def(node))
&& (sym instanceof AST_PropAccess || sym.name in lvalues)
|| may_throw && node.has_side_effects(compressor)
|| (side_effects || !replace_all)
&& (parent instanceof AST_Binary && lazy_op(parent.operator)
|| parent instanceof AST_Case
|| parent instanceof AST_Conditional
|| parent instanceof AST_If)) {
if (!(node instanceof AST_Scope)) descend(node, scanner);
abort = true;
return node;
}
// Skip (non-executed) functions and (leading) default case in switch statements
if (node instanceof AST_Default || node instanceof AST_Scope) return node;
// Skip (non-executed) functions
if (node instanceof AST_Scope) return node;
});
var multi_replacer = new TreeTransformer(function(node) {
if (abort) return node;
@@ -1000,6 +1015,7 @@ merge(Compressor.prototype, {
replace_all = def.references.length - def.replaced == 1;
}
var side_effects = value_has_side_effects(candidate);
var may_throw = candidate.may_throw(compressor);
var funarg = candidate.name instanceof AST_SymbolFunarg;
var hit = funarg;
var abort = false, replaced = 0, can_replace = !args || !hit;
@@ -2200,15 +2216,6 @@ merge(Compressor.prototype, {
def(AST_Constant, return_false);
def(AST_This, return_false);
def(AST_Call, function(compressor){
if (!this.is_expr_pure(compressor)) return true;
for (var i = this.args.length; --i >= 0;) {
if (this.args[i].has_side_effects(compressor))
return true;
}
return false;
});
function any(list, compressor) {
for (var i = list.length; --i >= 0;)
if (list[i].has_side_effects(compressor))
@@ -2219,6 +2226,10 @@ merge(Compressor.prototype, {
def(AST_Block, function(compressor){
return any(this.body, compressor);
});
def(AST_Call, function(compressor){
return !this.is_expr_pure(compressor)
|| any(this.args, compressor);
});
def(AST_Switch, function(compressor){
return this.expression.has_side_effects(compressor)
|| any(this.body, compressor);
@@ -2243,8 +2254,7 @@ merge(Compressor.prototype, {
def(AST_SimpleStatement, function(compressor){
return this.body.has_side_effects(compressor);
});
def(AST_Defun, return_true);
def(AST_Function, return_false);
def(AST_Lambda, return_false);
def(AST_Binary, function(compressor){
return this.left.has_side_effects(compressor)
|| this.right.has_side_effects(compressor);
@@ -2282,14 +2292,121 @@ merge(Compressor.prototype, {
|| this.property.has_side_effects(compressor);
});
def(AST_Sequence, function(compressor){
return this.expressions.some(function(expression, index) {
return expression.has_side_effects(compressor);
});
return any(this.expressions, compressor);
});
def(AST_Definitions, function(compressor){
return any(this.definitions, compressor);
});
def(AST_VarDef, function(compressor){
return this.value;
});
})(function(node, func){
node.DEFMETHOD("has_side_effects", func);
});
// determine if expression may throw
(function(def){
def(AST_Node, return_true);
def(AST_Constant, return_false);
def(AST_EmptyStatement, return_false);
def(AST_Lambda, return_false);
def(AST_SymbolDeclaration, return_false);
def(AST_This, return_false);
function any(list, compressor) {
for (var i = list.length; --i >= 0;)
if (list[i].may_throw(compressor))
return true;
return false;
}
def(AST_Array, function(compressor){
return any(this.elements, compressor);
});
def(AST_Assign, function(compressor){
return this.operator != "=" && this.left.may_throw(compressor)
|| this.right.may_throw(compressor);
});
def(AST_Binary, function(compressor){
return this.left.may_throw(compressor)
|| this.right.may_throw(compressor);
});
def(AST_Block, function(compressor){
return any(this.body, compressor);
});
def(AST_Call, function(compressor){
if (any(this.args, compressor)) return true;
if (this.is_expr_pure(compressor)) return false;
if (this.expression.may_throw(compressor)) return true;
return !(this.expression instanceof AST_Lambda)
|| any(this.expression.body, compressor);
});
def(AST_Case, function(compressor){
return this.expression.may_throw(compressor)
|| any(this.body, compressor);
});
def(AST_Conditional, function(compressor){
return this.condition.may_throw(compressor)
|| this.consequent.may_throw(compressor)
|| this.alternative.may_throw(compressor);
});
def(AST_Definitions, function(compressor){
return any(this.definitions, compressor);
});
def(AST_Dot, function(compressor){
return this.expression.may_throw_on_access(compressor)
|| this.expression.may_throw(compressor);
});
def(AST_If, function(compressor){
return this.condition.may_throw(compressor)
|| this.body && this.body.may_throw(compressor)
|| this.alternative && this.alternative.may_throw(compressor);
});
def(AST_LabeledStatement, function(compressor){
return this.body.may_throw(compressor);
});
def(AST_Object, function(compressor){
return any(this.properties, compressor);
});
def(AST_ObjectProperty, function(compressor){
return this.value.may_throw(compressor);
});
def(AST_Sequence, function(compressor){
return any(this.expressions, compressor);
});
def(AST_SimpleStatement, function(compressor){
return this.body.may_throw(compressor);
});
def(AST_Sub, function(compressor){
return this.expression.may_throw_on_access(compressor)
|| this.expression.may_throw(compressor)
|| this.property.may_throw(compressor);
});
def(AST_Switch, function(compressor){
return this.expression.may_throw(compressor)
|| any(this.body, compressor);
});
def(AST_SymbolRef, function(compressor){
return !this.is_declared(compressor);
});
def(AST_Try, function(compressor){
return any(this.body, compressor)
|| this.bcatch && this.bcatch.may_throw(compressor)
|| this.bfinally && this.bfinally.may_throw(compressor);
});
def(AST_Unary, function(compressor){
if (this.operator == "typeof" && this.expression instanceof AST_SymbolRef)
return false;
return this.expression.may_throw(compressor);
});
def(AST_VarDef, function(compressor){
return this.value.may_throw(compressor);
});
})(function(node, func){
node.DEFMETHOD("may_throw", func);
});
// determine if expression is constant
(function(def){
function all(list) {

84
test/compress/collapse_vars.js
View File

@@ -69,10 +69,11 @@ collapse_vars_side_effects_1: {
log(x, s.charAt(i++), y, 7);
}
function f4() {
var i = 10,
var log = console.log.bind(console),
i = 10,
x = i += 2,
y = i += 3;
console.log.bind(console)(x, i += 4, y, i);
log(x, i += 4, y, i);
}
f1(), f2(), f3(), f4();
}
@@ -152,7 +153,7 @@ collapse_vars_issue_721: {
collapse_vars:true, sequences:true, properties:true, dead_code:true, conditionals:true,
comparisons:true, evaluate:true, booleans:true, loops:true, unused:true, hoist_funs:true,
keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true,
reduce_funcs: true, reduce_vars:true
reduce_funcs: true, reduce_vars:true, passes:2
}
input: {
define(["require", "exports", 'handlebars'], function (require, exports, hb) {
@@ -675,8 +676,8 @@ collapse_vars_lvalues: {
function f4(x) { var a = (x -= 3); return x + a; }
function f5(x) { var w = e1(), v = e2(), c = v = --x; return (w = x) - c; }
function f6(x) { var w = e1(), v = e2(); return (v = --x) - (w = x); }
function f7(x) { var w = e1(); return (w = x) - (e2() - x); }
function f8(x) { var w = e1(); return (w = x) - (e2() - x); }
function f7(x) { var w = e1(), v = e2(); return (w = x) - (v - x); }
function f8(x) { var w = e1(), v = e2(); return (w = x) - (v - x); }
function f9(x) { var w = e1(); return e2() - x - (w = x); }
}
}
@@ -685,7 +686,7 @@ collapse_vars_lvalues_drop_assign: {
options = {
collapse_vars:true, sequences:true, properties:true, dead_code:true, conditionals:true,
comparisons:true, evaluate:true, booleans:true, loops:true, unused:true, hoist_funs:true,
keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true
keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true, passes:3
}
input: {
function f0(x) { var i = ++x; return x += i; }
@@ -706,10 +707,10 @@ collapse_vars_lvalues_drop_assign: {
function f3(x) { var a = (x -= 3); return x + a; }
function f4(x) { var a = (x -= 3); return x + a; }
function f5(x) { e1(), e2(); var c = --x; return x - c; }
function f6(x) { e1(), e2(); return --x - x; }
function f7(x) { e1(); return x - (e2() - x); }
function f8(x) { e1(); return x - (e2() - x); }
function f9(x) { e1(); return e2() - x - x; }
function f6(x) { return e1(), e2(), --x - x; }
function f7(x) { return e1(), x - (e2() - x); }
function f8(x) { return e1(), x - (e2() - x); }
function f9(x) { return e1(), e2() - x - x; }
}
}
@@ -1767,11 +1768,10 @@ switch_case: {
}
expect: {
function f(x, y, z) {
var c = z;
switch (x()) {
default: d();
case y(): e();
case c: f();
case z: f();
}
}
}
@@ -2195,7 +2195,7 @@ issue_315: {
expect: {
console.log(function() {
var w, _i, _len, _ref, _results;
for (_results = [], _i = 0, _len = (_ref = "test".trim().split(" ")).length; _i < _len ; _i++)
for (_ref = "test".trim().split(" "), _results = [], _i = 0, _len = _ref.length; _i < _len ; _i++)
w = _ref[_i], _results.push(w.toLowerCase());
return _results;
}());
@@ -3108,8 +3108,8 @@ issue_2437: {
return Object.defineProperty(XMLHttpRequest.prototype, "onreadystatechange", xhrDesc || {}),
result;
}
var req, detectFunc = function() {};
(req = new XMLHttpRequest()).onreadystatechange = detectFunc;
var req = new XMLHttpRequest(), detectFunc = function() {};
req.onreadystatechange = detectFunc;
result = req[SYMBOL_FAKE_ONREADYSTATECHANGE_1] === detectFunc;
req.onreadystatechange = null;
}();
@@ -3675,3 +3675,57 @@ issue_2506: {
}
expect_stdout: "1"
}
issue_2571_1: {
options = {
collapse_vars: true,
toplevel: true,
}
input: {
var b = 1;
try {
var a = function f0(c) {
throw c;
}(2);
var d = --b + a;
} catch (e) {
}
console.log(b);
}
expect: {
var b = 1;
try {
var a = function f0(c) {
throw c;
}(2);
var d = --b + a;
} catch (e) {
}
console.log(b);
}
expect_stdout: "1"
}
issue_2571_2: {
options = {
collapse_vars: true,
toplevel: true,
}
input: {
try {
var a = A, b = 1;
throw a;
} catch (e) {
console.log(b);
}
}
expect: {
try {
var a = A, b = 1;
throw a;
} catch (e) {
console.log(b);
}
}
expect_stdout: "undefined"
}